Although not all people experience love at first sight, it is clearly a real phenomenon. Many people can attest to the fact that they fell in love at first sight. Some lucky people have felt love at first sight. It is such a common experience, everyone has heard of love at first sight, even if they haven't experienced it for themselves.
Love at first sight is not possible in the real world. Love at first sight is just you being attracted to their looks and not their real self. You just feel in love with the person you think they are. You know nothing about the person and you are saying its love at first sight... What if you don't like that one thing that you really hate that person does. So no love at first sight is not possible.
It should be called infatuated at first sight. You might fall in love later, but not necessarly. Most relationships start with liking or lusting someone, though. It's instant attraction, but not love. I have never had a crush on anyone I hadn't at least had a conversation with them. Trust me, it's infatuation not love.
Love is based on the experience you have with the individual. Those experiences can either be directly or indirectly. You may have witness that person being respectful and caring towards someone else. It could also be a case where this person has proved time and time again that they mean you well. You cannot tell if someone is a patient person at first glance unless of course they had demonstrated patience towards something that most people would not normally be able to tolerate.
Your first impression of someone (before you speak to them or know anything about them) comes from the way they look, and to claim that you can fall in love with them just from that implies looks are the most important part of a relationship- which is simply untrue. To really love someone, you have to connect with them; find out about their personality, interests, qualities, flaws- and that takes time. You can't go from not being in love to being in love in a split second- it doesn't work like that. You can be attracted to someone as soon as you see them, but that attraction is based solely on looks and you might find that you don't actually like them as a person- therefore you don't fall in love with them.
No, love at first sight is not real, because true love is based on something more stable than how a person looks. True love also lasts over time. It is enduring. A person cannot know enough about a person at first sight to know if they truly love them or not.